Systems and methods for separating tissue in corneal transplant procedures

ABSTRACT

A device for separating tissue in an eye includes a body configured to be positioned on the eye surface. The body receives air from one or more air supplies. The body includes one or more air supply channels. The separation device includes a plurality of needles extending from the body. Each needle includes a proximal opening, a distal opening, and a passageway extending between the proximal and distal openings. The proximal openings of the needles are coupled to the one or more air supply channels. The distal openings of the needles are spaced from the body to be positioned in eye tissue. The one or more air supply channels direct the air from the one or more air supplies into the proximal openings, through the passageways, and out the distal openings of the needles and into the eye tissue. The air applies a pressure to separate the eye tissue.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of, and priority to, U.S.Provisional Patent Application Ser. No. 62/520,333, filed Jun. 15, 2017,the contents of which are incorporated entirely herein by reference.

BACKGROUND Field

The present disclosure pertains to systems and methods for transplantinga cornea to treat disorders of the eye, and more particularly, tosystems and methods for separating tissue in corneal transplantprocedures.

Description of Related Art

Various disorders of the eye may result from diseased/damaged cornealtissue. The diseased/damaged corneal tissue can affect vision byscattering and/or distorting light and causing glare and/or blurredvision. In some cases, proper vision can only be restored by a cornealtransplant which replaces the diseased/damaged corneal tissue withhealthy tissue from an organ donor.

SUMMARY

Aspects of the present disclosure provide systems and methods forseparating tissue to remove diseased/damaged tissue from a recipientcornea in corneal transplant procedures. For instance, such systems andmethods may separate stromal tissue from Descemet's membrane for deepanterior lamellar keratoplasty (DALK).

According to one embodiment, a system for separating tissue in an eyeincludes a separation device. The separation device includes a bodyconfigured to be positioned on a surface of an eye. The body isconfigured to receive air from one or more air supplies. The bodyincluding one or more air supply channels. The separation deviceincludes a plurality of needles extending from the body. Each needleincludes a proximal opening, a distal opening, and a passagewayextending between the proximal opening and the distal opening. Theproximal openings of the needles are coupled to the one or more airsupply channels of the body. The distal openings of the needles arespaced from the body to be positioned in tissue of the eye when the bodyis positioned on the surface of the eye. The one or more air supplychannels are configured to direct the air from the one or more airsupplies into the proximal openings, through the passageways, and outthe distal openings of the needles and into the tissue of the eye. Theair applies a pressure to separate the tissue of the eye. In someembodiments, the distal openings of the needles are spaced from the bodysuch that when the body is positioned on the surface of the eye, thedistal openings are positioned between a stroma and Descemet's membraneof a cornea of the eye.

According to another embodiment, A method for separating tissue in aneye includes positioning a body of a separation device on a surface ofan eye such that a plurality of needles extending from the body moveinto tissue of the eye. The method includes coupling the body to one ormore air supplies. The method includes operating the one or more airsupplies to deliver air to one or more air supply channels of the body.Each needle includes a proximal opening, a distal opening, and apassageway extending between the proximal opening and the distalopening. The proximal openings of the needles are coupled to the one ormore air supply channels of the body. The distal openings of the needlesspaced from the body and positioned in the tissue of the eye. The one ormore air supply channels direct the air from the one or more airsupplies into the proximal openings, through the passageways, and outthe distal openings of the needles and into the tissue of the eye. Theair applies a pressure to separate the tissue of the eye. Positioningthe body of the separation device on the surface of the eye may causethe distal openings of the needles to be positioned between a stroma andDescemet's membrane of a cornea of the eye to separate the stroma fromthe Descemet's membrane.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an example corneal transplant procedure where stromaltissue is separated from Descemet's membrane to remove tissue from arecipient cornea, according to aspects of the present disclosure.

FIG. 2 illustrates an example separation device including a plurality ofneedles that apply air from an air supply between the stroma andDescemet's membrane to cause a separation therebetween, according toaspects of the present disclosure.

FIG. 3A illustrates an example pattern of needles that applies air froman air supply between the stroma and Descemet's membrane to cause aseparation therebetween, according to aspects of the present disclosure.

FIG. 3B illustrates another example pattern of needles that applies airfrom an air supply between the stroma and Descemet's membrane to cause aseparation therebetween, according to aspects of the present disclosure.

FIG. 4 illustrates the separation device of FIG. 1 stably coupled to thecornea via an example staging device, according to aspects of thepresent disclosure.

FIG. 5 illustrates another example separation device including more thanone subset of needles that applies air from more than one air supplybetween the stroma and Descemet's membrane to cause a separationtherebetween, according to aspects of the present disclosure.

DETAILED DESCRIPTION

Various disorders of the eye may result from diseased/damaged cornealtissue. The diseased/damaged corneal tissue can affect vision byscattering and/or distorting light and causing glare and/or blurredvision. In some cases, proper vision can only be restored by a cornealtransplant which replaces the diseased/damaged corneal tissue withhealthy tissue from an organ donor.

From the outer (anterior) surface of the eye to the inner (posterior)parts, the structure of the cornea includes five layers: (1) epithelium(approximately 50 μm thick), (2) Bowman's layer (approximately 20 μmthick), (3) stroma (approximately 500 μm thick), (4) Descemet's membrane(approximately 10 μm thick), and (5) endothelium (approximately 5 μmthick). Penetrating keratoplasty (PK) involves a full-thicknesstransplant where all layers of a cornea from the epithelium to theendothelium are removed and replaced with a corneal implant. In PK, amanual dissection device known as a trephine may be employed to removethe full thickness of existing corneal tissue. The trephine may also beused to cut a donor cornea to provide the corneal implant thatdimensionally matches the removed corneal tissue. The corneal implant isthen positioned in place of the removed corneal tissue and sutured intoplace.

Deep anterior lamellar keratoplasty (DALK) is an alternative treatmentthat selectively replaces diseased/damaged tissue in an anterior portionof a recipient cornea. In particular, DLAK removes an anterior portionincluding the epithelium, Bowman's layer, and the stroma, but leaves aposterior portion including the native Descemet's membrane andendothelium in place. A dimensionally matching corneal implant from adonor cornea is then positioned in a bed formed by the removal of theanterior portion in the recipient cornea and sutured into place.

DALK is less invasive than PK and is preferred when the endothelium ishealthy. In contrast to the cells of the epithelium and the stroma, thecells of the endothelium cannot regenerate. With DALK, patients retaintheir own endothelium so the risk of rejection by the immune system maybe dramatically reduced.

FIG. 1 illustrates a recipient cornea 10 including epithelium 12 a,stroma 12 b, Descemet's membrane 12 c, and endothelium 12 d. Accordingto aspects of the present disclosure, embodiments apply air between thestroma 12 b and Descemet's membrane 12 c. The air applies sufficientpressure to cause a separation 14 between the stroma 12 b and theDescemet's membrane 12 c. After the separation 14 is created, a cuttingdevice can be applied to the recipient cornea 10 to make a cut 16 thatextends from the epithelium 12 a to the separation 14. For instance, thecutting device may be a trephine with a blade that makes a substantiallycircular cut at each depth (parallel to the x-y plane shown in FIG. 1)from the epithelium 12 a to the separation 14. The separation 14 and thecut 16 define an anterior portion 10 a of corneal tissue that is removedfrom the recipient cornea 10. After removal of the anterior portion 10a, a posterior portion 10 b (including the Descemet's membrane 12 c andthe endothelium 12 d) is left in place to define a bed for receiving acorneal implant for DALK.

FIG. 2 illustrates an example separation device 100 for separating thestroma 12 b and the Descemet's membrane 12 c to remove tissue from therecipient cornea 10. The separation device 100 includes a body 110 and aplurality of needles (or micro-needles) 120 that extend from the body110. The needles 120 may be formed from stainless steel with theappropriate gauge and the body 110 may be formed from stainless steel ora plastic.

The body 110 can be positioned on the outer surface of the recipientcornea 10, i.e., the epithelium 12 a. In particular, the separationdevice 100 is lowered in the negative z-direction as shown in FIG. 2 toposition the body 110 on the epithelium 12 a. The body 110 may include acontact surface 110 a that is contoured to accommodate the shape of theepithelium 12 a.

As the separation device 100 is lowered onto the epithelium 12 a, theneedles 120 penetrate the recipient cornea 10, passing through theepithelium 12 a, Bowman's layer (not shown), and the stroma 12 b. Eachneedle 120 includes a passageway 122 that extends from a proximalopening 120 a to a distal opening 120 b. The proximal opening 120 a ofeach needle 120 is positioned at or in the body 110. Meanwhile, thedistal opening 120 b of each needle 120 is positioned at a distance fromthe body 110. When the body 110 is positioned on the epithelium 12 a,the distal opening 120 b is positioned approximately between the stroma12 b and the Descemet's membrane 12 c. For instance, the needles 120 mayextend to a depth of approximately 570 μm in the recipient cornea 10 toposition the distal openings 120 b between the stroma 12 b and theDescemet's membrane 12 c. Various separation devices with varyingdimensions, e.g., different needle lengths, may be provided toaccommodate specific patient needs and characteristics, e.g., differentthicknesses for corneal layers.

The body 110 includes a port 112 that can be coupled to an air supply200 via a connecting tube 202. The body 110 includes one or more airsupply channels 114 that connect the port 112 to the proximal openings120 a of the needles 120. The air supply 200 can be operated to delivera predetermined amount of air through the proximal openings 120 a. Forinstance, the air supply 200 may be a syringe with a plunger than can beoperated to push air into the connecting tube 202 and through the port112 and the air supply channels 114.

The air delivered from the air supply 200 travels through the needles120, i.e., into the proximal openings 120 a, through the passageways122, and out the distal openings 120 b. When the body 110 is positionedon the epithelium 12 a, the air exits the distal openings 120 b intoareas between the stroma 12 b and the Descemet's membrane 12 c. Thedistal openings 120 b are positioned at various respective locationsbetween the stroma 12 b and the Descemet's membrane 12 c. Specifically,the body 110 is positioned on the epithelium 12 a so that the needles120 deliver the air from the air supply 200 to desired locations. Theair creates sufficient pressure at the desired locations to separate thestroma 12 b from the Descemet's membrane 12 c. Advantageously, the useof the plurality of needles 120 distributes air pressure across thedesired locations for more efficient and precise separation of thestroma 12 b from the Descemet's membrane 12 c.

As described above, after the stroma 12 b is separated from theDescemet's membrane 12 c, a cutting device, e.g., a trephine, can beapplied to the recipient cornea 10 to make a cut that extends from theepithelium 12 a to the separation. As such, the anterior portion 10 a ofthe recipient cornea 10 can be removed to allow for a corneal implant.

Aspects of the separation device 100, e.g., the air supply channels 114of the body 110 and/or the needles 120, may be configured to deliver theair with substantially similar airflow at each distal opening 120 b.Alternatively, aspects of the separation device 100 may be configured todeliver the air with varying airflows via different respective needles120 for more effective separation at particular areas between the stroma12 b and the Descemet's membrane 12 c. For instance, a first needle mayhave a first passageway with a smaller cross-sectional area than asecond passageway of a second needle, so that the airflow through thefirst needle has a greater velocity than the airflow through the secondneedle.

FIG. 3A illustrates an example pattern 102 a of needles 120 extendingfrom the body 110 to apply air to desired locations between the stroma12 b and the Descemet's membrane 12 c. In particular, the needles 120are arranged uniformly in a grid. The number of needles 120 per area issubstantially uniform across the pattern 102 a (excluding the edges). Assuch, if each needle 120 provides substantially the same airflow, a moreuniform amount of air can be delivered across the pattern 102 a(excluding the edges).

Alternatively, FIG. 3B illustrates another example pattern 102 b ofneedles 120 extending from the body 110. In particular, the needles 120are arranged in lines that extend radially outward from a center.Approaching the center of the pattern 102 b, the number of needles 120per area increases. Thus, if each needle 120 provides substantially thesame airflow, more air is delivered at the center of the pattern 102 b.The pattern 102 may be employed, for instance, if more air pressure isdesired at the center for more effective separation of the stroma 12 band the Descemet's membrane 12 c.

Although FIGS. 3A-B illustrate specific needle patterns 102 a, b, theneedles 120 in other embodiments may be arranged according to otherpatterns. For instance, the needles 120 may be arranged to deliver airaccording to non-circular and/or asymmetric patterns. The needles may bearranged with non-uniform spacing between the needles across thepattern. The number of needles 120 per area may vary across the patternin any manner to deliver more air where desired. Furthermore, inaddition to being arranged according to a particular pattern, differentneedles 120 may deliver the air with varying respective airflows.

As described above, the body 110 of the separation device 100 ispositioned on the epithelium 12 a to deliver the air to desiredlocations via the needles 120. To keep the body 110 in a stable positionon the epithelium 12 a for precise operation of the separation device100, embodiments may include a staging device that couples the body 110to the cornea 10 and minimizes relative motion between the body 12 a andthe cornea 10.

FIG. 4 illustrates an example staging device 300 for positioning theseparation device 100. The staging device 300 includes a body 310 thatholds the separation device 100. For instance, the body 310 may be aring with a central aperture in which the body 110 of the separationdevice 100 can be fixedly positioned.

The body 310 also includes a contact surface 310 a that is contoured toengage the epithelium 12 a. Additionally, the body 310 includes a port302 that can be coupled to a vacuum source 400 via a connecting tube402. Furthermore, the body 310 includes one or more vacuum channels 304that are connected to the port 302. The vacuum channels 304 include oneor more openings 304 a at the contact surface 310 a.

The vacuum source 400 can be operated to generate negative pressure inthe vacuum channels 304. For instance, the vacuum source 400 may be asyringe with a plunger than can be operated to draw air from the vacuumchannels 304 via the port 302 and the connecting tube 402. The negativepressure creates suction at the one or more openings 304 a, causing thecontact surface 310 a of the staging device 300 to engage the epithelium12 a. This engagement stably positions the staging device 300 and thusthe separation device 100 on the epithelium 12 a. As such, relativemovement between the separation device 100 and the cornea 10 can beminimized. After the separation device 100 is operated to separate thestroma 12 b from the Descemet's membrane 12 c as described above, thevacuum source 400 can be operated to release the staging device 300 andthe separation device 100 from the cornea 10.

As described above, the separation device 100 may be coupled to the airsupply 200 to deliver air through each needle 120. Other embodiments,however, may employ more than one air supply to deliver air to theneedles. For instance, FIG. 5 illustrates another example separationdevice 500 which is coupled to more than one air supply. The separationdevice 500 includes a body 510 and a plurality of needles 520 a, b.Similar to the separation device 100 described above, the needles 520 a,b extend to areas between the stroma 12 b and the Descemet's membrane 12c when the body 510 is positioned on the epithelium 12 a. Thus, theneedles 520 a, b can apply air to separate the stroma 12 b from theDescemet's membrane 12 c. Unlike the separation device 100, however, theseparation device 500 includes a first port 512 a that can be coupled tothe first air supply 200 via the first connecting tube 202 and a secondport 512 b that can be coupled to a second air supply 600 via a secondconnecting tube 602.

As shown in FIG. 5, the separation device 500 includes a first subset ofneedles 520 a and a second subset of needles 520 b. The body 510includes a first subset of one or more air supply channels 514 a thatconnect the port 512 a to the first subset of needles 520 a.Additionally, the body 510 includes a second subset of one or more airsupply channels 514 b that connect the port 512 b to the second subsetof needles 520 b.

The first subset of needles 520 a and the second subset of needles 520 bare separately coupled to the first air supply 200 and the second airsupply 600, respectively. As such, the first air supply 200 can beoperated to deliver a first amount of air to the first subset of needles520 a. Meanwhile, the second air supply 600 can be separately operatedto deliver a second amount of air to the second subset of needles 520 b.As described above, the first air supply 200 may be a syringe with aplunger than can be operated to push air into the connecting tube 202and through the port 512 a and the air supply channels 514 a. Similarly,the second air supply 600 may also be a syringe.

Advantageously, the use of more than one air supply allows differentamounts of air to be delivered to different subsets of needles,respectively. This provides control over the amounts of air delivered todifferent areas between the stroma 12 b and the Descemet's membrane 12c. For instance, as shown in FIG. 5, the first subset of needles 520 amay be positioned on the periphery of the needle pattern for theseparation device 500, while the second subset of needles 520 b may bepositioned in the center of the needle pattern. As such, if less (ormore) air is desired on the periphery of the needle pattern to separatethe stroma 12 b from the Descemet's membrane 12 c, the first air supply200 may be selectively operated to deliver, to the first subset ofneedles 520 a, a lesser (or greater) amount of air than the amount ofair delivered to the second subset of needles 520 b with the second airsupply 600.

Although the first air supply 200 and the second air supply 600 may beoperated to deliver air to the needles 520 a, b substantiallysimultaneously, it is contemplated that the first air supply 200 and thesecond air supply 600 may be operated at different times to separatedifferent areas of the stroma 12 b from the Descemet's membrane 12 cduring different temporal stages. For instance, the first air supply 200may be operated at a first time to separate the stroma 12 b from theDescemet's membrane 12 c on the periphery of the needle pattern, and thesecond air supply 600 may be subsequently operated at a second time toseparate the stroma 12 b from the Descemet's membrane 12 c at the centerof the needle pattern.

In general, the use of more than one air supply can provide greatercontrol over the delivery of air via different needles. Although theseparation device 500 in FIG. 5 may employ two air supplies 200, 600 fortwo subsets of needles 520 a, b, other embodiments may include more thantwo air supplies for more than two subsets of needles. A subset ofneedles may include one or more needles. It is also contemplated that asubset of needles may be coupled to more than one air supply. Moreover,although the first subset of needles 520 a may be positioned on theperiphery of the needle pattern and the second subset of needles 520 bmay be positioned at the center of the needle pattern, in otherembodiments the needles in a subset connected to a particular air supplymay be positioned in any location(s) in the needle pattern.

Although the air supplies and vacuum supply described above may includesyringes, other embodiments may employ other devices, e.g., small pumps,to deliver air to the separation device and/or generate a negativepressure in the staging device.

Although the example embodiments described above may involve separatingstromal tissue from Descemet's membrane in vivo for deep anteriorlamellar keratoplasty (DALK), aspects of the present disclosure may beemployed to separate other tissue layers for other procedures. Forinstance, aspects of the present disclosure may be applied to separatetissue layers ex vivo in donor cornea to form a corneal implant.

While the present disclosure has been described with reference to one ormore particular embodiments, those skilled in the art will recognizethat many changes may be made thereto without departing from the spiritand scope of the present disclosure. Each of these embodiments andobvious variations thereof is contemplated as falling within the spiritand scope of the invention. It is also contemplated that additionalembodiments according to aspects of the present disclosure may combineany number of features from any of the embodiments described herein.

We claim:
 1. A system for separating tissue in an eye, comprising: aseparation device including: a body configured to be positioned on asurface of an eye, the body configured to receive air from one or moreair supplies, the body including one or more air supply channels; and aplurality of needles extending from the body, each needle including aproximal opening, a distal opening, and a passageway extending betweenthe proximal opening and the distal opening, the proximal openings ofthe needles coupled to the one or more air supply channels of the body,the distal openings of the needles spaced from the body to be positionedin tissue of the eye when the body is positioned on the surface of theeye, wherein the one or more air supply channels of the body areconfigured to direct the air from the one or more air supplies into theproximal openings, through the passageways, and out the distal openingsof the needles and into the tissue of the eye, the air applying apressure to separate the tissue of the eye.
 2. The system of claim 1,wherein the distal openings of the needles are spaced from the body suchthat when the body is positioned on the surface of the eye, the distalopenings are positioned between a stroma and Descemet's membrane of acornea of the eye.
 3. The system of claim 2, wherein the distal openingsof the needles are spaced approximately 570 μm from the body.
 4. Thesystem of claim 1, wherein the body includes one or more portsconfigured to be coupled to the one or more air supplies.
 5. The systemof claim 1, wherein each air supply includes a syringe.
 6. The system ofclaim 1, further comprising a staging device coupled to the body of theseparation device, the staging device configured to engage the surfaceof the eye and position the body stably on the surface of the eye. 7.The system of claim 6, further comprising a vacuum source coupled to thestaging device, the staging device including vacuum channels coupled tothe vacuum source and one or more negative pressure openings coupled tothe vacuum channels, the vacuum source being operable to generate anegative pressure at the negative pressure openings via the vacuumchannels, the negative pressure creating a suction between the negativepressure openings and the surface of the eye.
 8. The system of claim 7,wherein the vacuum source includes a syringe.
 9. The system of claim 1,wherein the body is configured to receive air from a first air supplyand a second air supply, the one or more air supply channels includes afirst set of one or more air supply channels coupled to the first airsupply and a second set of one or more air supply channels coupled tothe second air supply, the plurality of needles including a first subsetof needles and a second subset of needles, the first subset of needlesreceiving air from the first air supply via the first set of one or moreair supply channels, the second subset of needles receiving air from thesecond air supply via the second set of one or more air supply channels.10. The system of claim 9, wherein the air from the first air supply isdifferent in amount than the air from the second air supply.
 11. Thesystem of claim 1, wherein the plurality of needles are arranged in asymmetric pattern.
 12. The system of claim 1, wherein the plurality ofneedles are arranged in a circular pattern.
 13. The system of claim 1,wherein the plurality of needles are arranged in a grid pattern.
 14. Thesystem of claim 1, wherein the plurality of needles are arranged in anasymmetric pattern.
 15. The system of claim 1, wherein the plurality ofneedles are arranged in a non-circular pattern.
 16. The system of claim1, wherein the plurality of needles are arranged with non-uniformspacing between the needles across a pattern.
 17. The system of claim 1,wherein the air directed out each of the distal openings of the needleshas substantially a same airflow.
 18. The system of claim 1, wherein theair directed out the distal opening of one of the needles has adifferent airflow than the air directed out the distal opening ofanother of the needles.
 19. A method for separating tissue in an eye,comprising: positioning a body of a separation device on a surface of aneye such that a plurality of needles extending from the body move intotissue of the eye; coupling the body to one or more air supplies; andoperating the one or more air supplies to deliver air to one or more airsupply channels of the body, wherein each needle includes a proximalopening, a distal opening, and a passageway extending between theproximal opening and the distal opening, the proximal openings of theneedles coupled to the one or more air supply channels of the body, thedistal openings of the needles spaced from the body and positioned inthe tissue of the eye, and the one or more air supply channels directthe air from the one or more air supplies into the proximal openings,through the passageways, and out the distal openings of the needles andinto the tissue of the eye, the air applying a pressure to separate thetissue of the eye.
 20. The method of claim 19, wherein positioning thebody of the separation device on the surface of the eye causes thedistal openings of the needles to be positioned between a stroma andDescemet's membrane of a cornea of the eye, and operating the one ormore air supplies separates the stroma from the Descemet's membrane.